Analytic Design of Multi-Phase Electric Machines with Independent H- Bridge Supply

This paper offers a guideline for the early design stages of multi-phase electric machines. All considerations refer to permanent magnet synchronous machines (PMSM) with tooth-wound coils. The coils are separately fed by H-bridge converters. Corresponding drive configurations provide a maximum of availability and control flexibility. Based on analytic modelling of the air gap magnetomotive force (MMF), feasible combinations of slot, pole, and phase numbers are suggested. Next, the extracted combinations are evaluated in terms of torque oscillation, radial forces, winding factor and unbalanced magnetic pull. The proposed set of design criteria appears in the form of analytic expressions, which are suited to the creation of design tables. Altogether, the approach allows an effective preselection of promising design solutions and supports further finite-element optimization steps.